From the inception of freezing-point determination by Raoult, van't Hoff, Beckmann, et al., all freezing-point work has been done at constant temperature. The heat sink or heat source has been carefully controlled with improvements being made in thermostats and insulation to achieve an adiabatic condition during the freezing-point process. These methods have a limit on their inherent precision and repeatability because of overshooting, supercooling and other temperature reversals in the measurement cycle. Because of this, they are not adequate for working with very small samples, or for determining high molecular weights or precise chemical purity. As a result, other techniques are currently employed for such determinations.
It is accordingly, a general object of the present invention to provide an improved method for measuring the freezing-point of a liquid.
It is a specific object of the invention to provide a method for measuring the freezing point of a liquid in which non-adiabatic thermodynamics are employed in the chilling chamber to produce a more nearly true adiabatic condition in the liquid sample during nucleation.
It is another object of the invention to provide a method for measuring the freezing point of a liquid in which the net heat flow from the sample portion of the liquid under measurement is reduced at least during nucleation of the sample portion of the liquid.
It is a feature of the invention that the method can be used with very small samples and for determining higher molecular weights or precise chemical purity.
It is another feature of the invention that the method provides increased precision and repeatability over the prior art adiabatic freezing- and melting-point techniques.